1. Technical Field
The present invention relates generally to photosensitive polymers, more particularly to photosensitive polymers including fluorine, a resist composition containing the same and a patterning method using the resist composition.
2. Discussion of the Related Art
As semiconductor devices become more highly integrated and the manufacture of semiconductor devices becomes more complex, the ability to form fine patterns becomes more important. For instance, in semiconductor devices having a memory capacity of 1-gigabit or greater, a pattern size having a design rule of 0.1 μm or less is needed. Such pattern size is difficult to achieve using a conventional photoresist material and a KrF excimer laser (248 nm). A photolithography technique using ArF excimer laser (193 nm) as a new exposure light source has been proposed. The 193 nm photolithography technique can be applied to 0.1 μm level industry. To form still smaller patterns, a new photolithography technique to form patterns having a design rule of 0.1 or less is needed.
Further, the use of a F2 excimer laser (157 nm) applicable to 70 nm level photolithography technique has increased and new resist materials to use the F2 excimer laser (157 nm) have been proposed.
Resist materials used in the lithography using F2 (157 nm) excimer laser are required to meet several criteria, e.g., high transmittance for a light source of 157 nm or below, high dry etching resistance, good adhesion to underlying layers, high contrast, and capable of being developed using a conventional developer.
Polymers having the following formulas have been proposed as resist materials for 157 nm laser as follows: 
Polymers using tetrafluoroethylene (CF2CF2) monomer, as represented by Formula 4, exhibit very low absorbance to a wavelength of 157 nm and proposed as resist materials suitable for 157 nm lithography, which is described in Journal of photopolymer science and technology, Vol. 14, No. 4, pp 583-593, 2001 and Journal of photopolymer science and technology, Vol. 14, No. 4, pp 669-674, 2001.
Another polymer containing greater than 50% fluorine having a high transmittance at 157 nm, as represented by Formula 5, has been proposed, as described in “157 nm single layer resists based on advanced fluorinated polymers” Proc. SPIE 2002: 
However, photosensitive polymers have not satisfied the various requirements needed to be used as resist materials for F2 excimer laser,
Therefore, a need exists for photosensitive polymers having a high transmittance for F2 excimer (157nm) laser, a resist composition comprising the same for use in a shorter wavelength exposure light source of 157 nm or below, and pattern methods using the same.